1. Technical Field
The present invention relates to data communication networking devices, more particularly, to the data frame forwarding capability of a data network switch.
2. Background Art
A multiport data network switch conventionally permits data communication among a plurality of media stations in a local area network. Each station in the network is associated with a port of the switch. Data frames, or packets, are transferred between stations by means of data network switch media access control (MAC) circuitry, or xe2x80x9cengines,xe2x80x9d for each switch port. The network switch passes data frames received from a transmitting station to a destination station based on the header information in the received data frame. The switch can link the network to other networks through one or more predesignated switch ports. The capability thus exists for creating logical workgroups of users who may be physically separated from each other. The network switch includes switching logic for receiving and forwarding frames to the appropriate destinations. When all of the stations connected to the network are simultaneously operating, packet traffic on the shared path can be heavy with little time between packets. As the switch experiences congestion, data loss and switch latency pose a serious problem.
As a result, the system is less reliable.
There exists a need for a switching device that efficiently generates frame forwarding information for various types of data transmissions in a VLAN environment. There exists a need for a switching device that includes a decision making engine designed to support networks requiring a high data throughput. There is also a need for a switching device that employs a modular decision making engine that facilitates changes to the decision making logic. There is also a need for distributing the process of forwarding data frames to avoid processing bottlenecks in the system and to increase system reliability.
These and other needs are satisfied by the present invention, where a multiport switch includes a decision making engine used to make frame forwarding decisions, in part, by outputting forwarding information. The decision making engine is a designed in a pipelined, modular fashion so that multiple frames may be processed simultaneously.
According to one aspect of the present invention, a multiport switch is configured for processing a data frame. The multiport switch comprises a plurality of ports for outputting the data frame. The switch also includes a rules checker logic for generating, in a pipeline manner, a forwarding descriptor. The rules checker logic includes a destination address engine for outputting a port vector that selectively maps a destination address of the data frame to one or more of the ports. Moreover, the rules checker logic is configured to modify the port vector to output the forwarding descriptor. The forwarding descriptor contains the modified port vector. Because the rules checker logic possesses a modular, pipelined architecture, the data frame forwarding rate is enhanced.
Still another aspect of the present invention provides a method of forwarding a data frame in a switching system having a plurality of ports for outputting the data frame. The method comprises generating a port vector based upon a destination address of the data frame. The port vector designates one or more of the plurality of ports to output the data frame. The method also includes modifying the port vector to selectively add or remove port designations. Ultimately, a forwarding descriptor is output in a pipeline manner. This method advantageously outputs a forwarding descriptor efficiently, thereby increasing the data throughput of the multiport switch.
Additional advantages and novel features of the invention will be set forth in part in the description which follows, and in part may become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.